The invention relates generally to contact coupling assemblies and, more particularly, to a contact coupling assembly which provides an interface between an electrical system and a fiber optic system.
Because of their inherent capability of transmitting more data than a comparably sized electrical wire, fiber optic cable transmission lines have become more widely used. Since fiber optic cables do not produce electromagnetic interference and are not susceptible to radio frequency interference, they have become more desirable in avionic systems and many other types of systems in which noise interference can cause malfunction thereof. However, fiber optic cable transmission systems have an important disadvantage which is that their connections require precise alignment and scrupulous cleanliness in order to function properly. This disadvantage of fiber optic cable systems has, to a certain degree, obviated the advantages such systems have and prevented them from widespread use.
Some conventional fiber optic contact assemblies utilize diodes which employ pin contact pairs. Since such conventional contact assemblies are bulky and complex in construction, some prior art electro-optical transmission systems have been designed to utilize a simpler, generally standard electrical connector member. Examples of such electro-optical transmission lines are disclosed in U.S. Pat. No. 3,809,908 to Clanton and U.S. Pat. No. 3,878,397 to Clanton et al. The transmission line of the Clanton devices employ an optical fiber bundle with an integrated coaxial electrical contact assembly at each end of the bundle. The Clanton devices also employ a radiation emitting device at one end of the assemblies and an infrared photo diode at the other end in order to convert the signal to an optical signal from an electrical signal or to convert an electrical signal from an optical signal, depending on the particular end of the transmission line where the converter is located. The coaxial contact assemblies allow the Clanton line to be plugged directly into an electrical system. However, a primary disadvantage with the Clanton transmission line is that the fiber optic bundle is permanently secured in the contact assemblies necessitating that the line be directly plugged into an electrical system in order to allow signal transmission thereto. In addition, the Clanton transmission line must be installed as one assembly which can be difficult when connecting modular structures.
Other prior art optical transmission systems employ means to alter the transmission characteristics of the optical transmission line in order to accommodate the particular needs of the electrical system to which the optical transmission system is connected. An example of such an optical transmission system is disclosed in U.S. Pat. No. 4,691,368 to Eumurian, et al. The Eumurian system incorporates a pair of frequency compensating electrical circuits at each end of the optical transmission line terminal to accentuate high frequencies attentuated by the optical transmission line and to permit operation in a widened frequency band. However, a disadvantage of such systems is that incorporation of the electrical circuitry in the assembly substantially increases the cost and complexity of the assembly and decreases its reliability. In addition, the optical cables are permanently secured to the assemblies requiring that the entire connector assembly be plugged or unplugged directly to or from an electrical system.
In aircraft applications, periodic inspection of electrical and optical connections is typically required. For prior art electro-optical assemblies in Which the fiber optic cable is permanently secured to the connector assembly, inspection of the optical surfaces of the termini is not possible. For blind mate optical connector systems used in many avionic systems, frequent mating and unmating of the connectors result in failures or malfunctions of the interconnects. These failures and malfunctions include damage to or contamination of the optical surfaces, bent termini, cracked connector inserts and connector shells and failure of the termini retention mechanism allowing terminus pushback. Connectors typically generate minute particles of the base materials when the mating surfaces thereof rub against each other. These particles have been shown to cause failure in some optical interconnects. The particles can pit the optical surfaces, fracture the optical components within the connector and block the optical signal as it is propagating from one termini to the other. For this reason, it is imperative, particularly in aircraft applications where reliability is of utmost importance, that the optical surfaces of the connectors be carefully cleaned to eliminate such contaminating minute particles. However, blind mate connectors used in aircraft are often placed in areas where cleaning of the surfaces thereof is impractical or impossible. However, most of the blind mate interconnect components currently available are not easily cleaned and some require that the termini be removed and/or some parts removed, reassembled and re-inserted into the connector cavity for proper cleaning thereof. But, this process subjects the termination to possible contamination or possible damage since the wiring areas of equipment racks are cramped and sometimes do not have sufficient access to allow the proper use of tools.
What is therefore needed is an electro-optical contact coupling assembly in which the fiber optic termini thereof may be termini, cracked connector inserts and connector shells and failure of the termini retention mechanism allowing terminus pushback. Connectors typically generate minute particles of the base materials when the mating surfaces thereof rub against each other. These particles have been shown to cause failure in some optical interconnects. The particles can pit the optical surfaces, fracture the optical components within the connector and block the optical signal as it is propagating from one termini to the other. For this reason, it is imperative, particularly in aircraft applications where reliability is of utmost importance, that the optical surfaces of the connectors be carefully cleaned to eliminate such contaminating minute particles. However, blind mate connectors used in aircraft are often placed in areas where cleaning of the surfaces thereof is impractical or impossible. However, most of the blind mate interconnect components currently available are not easily cleaned and some require that the termini be removed and/or some parts removed, reassembled and re-inserted into the connector cavity for proper cleaning thereof. But, this process subjects the termination to possible contamination or possible damage since the wiring areas of equipment racks are cramped and sometimes do not have sufficient access to allow the proper use of tools.
What is therefore needed is an electro-optical contact assembly in which the fiber optic termini thereof may be easily removed therefrom for inspection and cleaning. An electro-optical contact assembly is also needed which utilizes generally standard electrical contact components allowing the assembly to be easily connected to various electrical systems.